There has been no shortage of speculation about the Air Force's secret space plane, the X-37B, since it had its nine-month mission indefinitely extended late last year.

Talk has focused on how the mysterious craft is likely the Pentagon's response to China's orbital entourage of space sensors and satellites that will provide vital data to its DF-21D "carrier killer" ballistic missile.

Those satellite sensors will serve China's anti-ship ballistic missiles, cyberwarfare operations, and anti-satellite weapons — and taking them out would be a priority in any military conflict with Beijing.

When the X-37B was brought up Shelton said “It is doing very well on orbit, and we don’t have an exact re-entry date for it. But it’s had a successful mission, and we are very happy with the performance.”

He declined to mention specifics on what that mission was, saying only that the system is "game changing," meaning it can make the difference between winning and losing an engagement.

Regarding its secrecy and black budget General Sheldon said “If you reveal budgets, you reveal sometimes the capabilities, the amount of technology that’s inserted into a program “I think in this case, it’s just a good strategic national security decision. Like we do other things of that ilk. Keep that budget to ourselves.”

To that end the Pentagon continues to say the secret aircraft is simply a "test bed for research."